A refresh someone asks for reads the feeds in full (#77)

Check every feed, a feed's refresh, pull to refresh and ipx fetch --force
all send force, which only skipped the not-due wait: the request still
carried the stored ETag and Last-Modified, so an unchanged feed answered
304 and was not read. anil-dash got no site icon from a refresh for this
reason. A forced scan now drops the validators; the scheduled scan keeps
them.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -34,6 +34,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   pinned: a tick when read, an envelope when not. It used to show the opposite.
 - In Directory and Popular, Subscribe is a plus again, not the tick that marks a feed you have.
 - A feed's refresh button looks like the buttons beside it, instead of standing out filled in.
+- Refreshing reads your feeds in full, instead of only asking each one whether it changed, so
+  a feed that has not changed is still read again.
 - A web page with some non-ASCII characters no longer hides the feed it links, or crashes looking for it.
 - Pulling the item list down to check for new items shows a spinner for a couple of seconds, and
   a second pull meanwhile does nothing, instead of no sign at all that the check started.